On the speakers I'm currently making I've gone a step further, there's two boxes connected by an aperiodic vent, ( the top one the same volume as the Vas of the driver, the bottom one double the Vas ) with a gap between ( that will be sealed by a foam gasket ), this means that I'll be able to change the area of the vent by sliding a thin sheet of metal inbetween, whilst playing music.
COOL ! kinda like "so" (?) I would expect well recorded drum tracks to be useful for adjustment. (That works in Karlson type with a rear lowpass "shelf")
https://i.imgur.com/cIIUi5j.png
https://i.imgur.com/cIIUi5j.png
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Depending on how hard people want to get after modeling that, instead of needing to do resistivity measurements or just fly by impedance alone, it might (?) be possible to "back into" useful filling resistivity values by just measuring spl & phase because you can export that from the filter wizard and have filling included. FWIW. HR port models are cylindrical and the high aspect ratio stuff like slits needs different modeling so my hunch is that slits are a no-go for modeling, but that's what I'd try before going full-airflow-measurement in case it's close enough. Might work well enough for less severe AR (?).
Ive been using several layers of grille cloth sandwiched with aluminum screening to create a "flow resistor" to put in place of the opening in my A26 Seas Dynaco clones. It seems to sound better than the fiberglass damping material and creates less audible air flow noise at higher cone excursions. As with anything, there is an efficiency tradeoff and you can hear it in earlier low end rollof, but the bass that is there sounds alot more resolving and tighter.
I'd like to experiment with a larger enclosure using a large higher Qts driver. I'm a little concerned with air flow noise using the DP enclosure tuning method. This looks alot like a very lossy port to me and likely could be calculated this way by overlaying the actual results with a specific loss factor for practical correction.
I also use loosely rolled up grille cloth behind my Vifa D75MX 3" mids in 1 cu ft chambers to lower the system Q to around .65 (compared to 1.2 without) which cleans up the lower mids substantially on this driver. This high Qts is the weakness of the D75MX (D7608-9200) mid and over-damping it transforms it into a very resolving driver that can be crossed around 600 Hz and handle more power down low than in a regular sealed chamber.
I'd like to experiment with a larger enclosure using a large higher Qts driver. I'm a little concerned with air flow noise using the DP enclosure tuning method. This looks alot like a very lossy port to me and likely could be calculated this way by overlaying the actual results with a specific loss factor for practical correction.
I also use loosely rolled up grille cloth behind my Vifa D75MX 3" mids in 1 cu ft chambers to lower the system Q to around .65 (compared to 1.2 without) which cleans up the lower mids substantially on this driver. This high Qts is the weakness of the D75MX (D7608-9200) mid and over-damping it transforms it into a very resolving driver that can be crossed around 600 Hz and handle more power down low than in a regular sealed chamber.